1 /**************************************************************************
2 * Copyright(c) 1998-2007, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
16 #include <TClonesArray.h>
18 #include "AliESDVertex.h"
19 #include "AliRunLoader.h"
20 #include "AliITSLoader.h"
21 #include "AliITSgeom.h"
22 #include "AliITSRecPoint.h"
23 #include "AliITSVertexerCosmics.h"
24 #include "AliStrLine.h"
26 //------------------------------------------------------------------------
27 // This class implements a method to construct a "fake" primary
28 // vertex for cosmic events in which the muon crosses the SPD inner
29 // layer (SPD1). A fake primary vertex is needed for the reconstruction,
30 // with e.g. AliITStrackerSA, of the two tracks produced by the muon
32 // We build pairs of clusters on SPD1 and define the fake vertex as
33 // the mid-point of the straight line joining the two clusters.
34 // We reject the backgroung by requiring at least one clusters on SPD2
35 // closer than fMaxDistOnSPD2 to the tracklet prolongation.
36 // We can reject (potentially pathological) events with the muon track
37 // tangential to the SPD1 layer by the requiring the radial position of
38 // the vertex to be smaller than fMaxVtxRadius.
39 // Due to background clusters, more than one vertex per event can
40 // be found. We consider the first found.
41 // The number of contributors set in the AliESDVertex object is the
42 // number of vertices found in the event; if this number is <1,
43 // the procedure could not find a vertex position and by default
44 // the vertex coordinates are set to (0,0,0) with large errors (100,100,100)
45 // Number of contributors = 0 --> No SPD1 tracklets matching criteria
46 // Number of contributors = -1 --> No SPD1 recpoints
48 // Origin: A.Dainese, andrea.dainese@lnl.infn.it
49 //-------------------------------------------------------------------------
51 ClassImp(AliITSVertexerCosmics)
53 //-------------------------------------------------------------------------
54 AliITSVertexerCosmics::AliITSVertexerCosmics():AliITSVertexer(),
63 // Default constructor
70 //--------------------------------------------------------------------------
71 AliESDVertex* AliITSVertexerCosmics::FindVertexForCurrentEvent(Int_t evnumber)
73 // Defines the AliESDVertex for the current event
76 AliRunLoader *rl =AliRunLoader::GetRunLoader();
77 AliITSLoader* itsLoader = (AliITSLoader*)rl->GetLoader("ITSLoader");
78 AliITSgeom* geom = itsLoader->GetITSgeom();
79 itsLoader->LoadRecPoints();
80 rl->GetEvent(evnumber);
82 TTree *rpTree = itsLoader->TreeR();
84 TClonesArray *recpoints=new TClonesArray("AliITSRecPoint",10000);
85 rpTree->SetBranchAddress("ITSRecPoints",&recpoints);
87 Double_t xclspd1[100],yclspd1[100],zclspd1[100],modclspd1[100];
88 Int_t nclspd1stored=0;
89 Double_t xclspd2[100],yclspd2[100],zclspd2[100],modclspd2[100];
90 Int_t nclspd2stored=0;
91 Int_t nrecpoints,nrecpointsSPD1=0;
93 Double_t gc[3]={0.,0.,0.};
94 Double_t lc[3]={0.,0.,0.};
97 Double_t x[100],y[100],z[100],p1[3],p2[3],p3[3];
99 Bool_t good,matchtospd2;
100 Double_t xvtx,yvtx,zvtx,rvtx;
102 for(Int_t imodule=fFirstSPD1; imodule<fLastSPD2; imodule++) { // SPD
103 rpTree->GetEvent(imodule);
104 geom->GetModuleId(imodule,lay,lad,det);
105 nrecpoints=recpoints->GetEntriesFast();
106 if(imodule<fLastSPD1) nrecpointsSPD1 += nrecpoints;
107 //printf("cosmics: module %d clusters %d\n",imodule,nrecpoints);
108 for(Int_t irp=0; irp<nrecpoints; irp++) {
109 AliITSRecPoint *rp=(AliITSRecPoint*)recpoints->UncheckedAt(irp);
110 // Local coordinates of this recpoint
111 lc[0]=rp->GetDetLocalX();
112 lc[2]=rp->GetDetLocalZ();
113 geom->LtoG(imodule,lc,gc); // global coordinates
114 if(lay==1) { // store SPD1 clusters
115 xclspd1[nclspd1stored]=gc[0];
116 yclspd1[nclspd1stored]=gc[1];
117 zclspd1[nclspd1stored]=gc[2];
118 modclspd1[nclspd1stored]=imodule;
121 if(lay==2) { // store SPD2 clusters
122 xclspd2[nclspd2stored]=gc[0];
123 yclspd2[nclspd2stored]=gc[1];
124 zclspd2[nclspd2stored]=gc[2];
125 modclspd2[nclspd2stored]=imodule;
128 if(nclspd1stored>100 || nclspd2stored>100)
129 AliFatal("More than 100 clusters per layer in SPD");
130 }// end clusters in a module
131 }// end SPD modules for a given event
133 // build fake vertices
135 // SPD1 - first cluster
136 for(Int_t i1spd1=0; i1spd1<nclspd1stored; i1spd1++) {
137 p1[0]=xclspd1[i1spd1]; p1[1]=yclspd1[i1spd1]; p1[2]=zclspd1[i1spd1];
138 // SPD1 - second cluster
139 for(Int_t i2spd1=i1spd1+1; i2spd1<nclspd1stored; i2spd1++) {
140 if(modclspd1[i1spd1]==modclspd1[i2spd1]) continue;
141 p2[0]=xclspd1[i2spd1]; p2[1]=yclspd1[i2spd1]; p2[2]=zclspd1[i2spd1];
142 // look for point on SPD2
143 AliStrLine spd1line(p1,p2,kTRUE);
144 matchtospd2 = kFALSE;
145 for(Int_t ispd2=0; ispd2<nclspd2stored; ispd2++) {
146 p3[0]=xclspd2[ispd2]; p3[1]=yclspd2[ispd2]; p3[2]=zclspd2[ispd2];
147 //printf(" %f\n",spd1line.GetDistFromPoint(p3));
148 if(spd1line.GetDistFromPoint(p3)<fMaxDistOnSPD2)
149 { matchtospd2 = kTRUE; break; }
151 if(!matchtospd2) continue;
152 xvtx = 0.5*(xclspd1[i1spd1]+xclspd1[i2spd1]);
153 yvtx = 0.5*(yclspd1[i1spd1]+yclspd1[i2spd1]);
154 zvtx = 0.5*(zclspd1[i1spd1]+zclspd1[i2spd1]);
155 rvtx = TMath::Sqrt(xvtx*xvtx+yvtx*yvtx);
156 if(rvtx>fMaxVtxRadius) continue;
158 for(Int_t iv=0; iv<nvtxs; iv++) {
159 if(TMath::Sqrt((xvtx- x[iv])*(xvtx- x[iv])+
160 (yvtx- y[iv])*(yvtx- y[iv])+
161 (zvtx- z[iv])*(zvtx- z[iv])) < fMinDist2Vtxs)
170 } // SPD1 - second cluster
171 } // SPD1 - first cluster
174 Double_t pos[3]={0.,0.,0.};
175 Double_t err[3]={100.,100.,100.};
184 if(!nrecpointsSPD1) nvtxs=-1;
185 fCurrentVertex = new AliESDVertex(pos,err,"cosmics");
186 fCurrentVertex->SetNContributors(nvtxs);
187 fCurrentVertex->SetTitle("cosmics fake vertex");
189 //if(nvtxs>0) fCurrentVertex->Print();
192 itsLoader->UnloadRecPoints();
194 return fCurrentVertex;
196 //-------------------------------------------------------------------------
197 void AliITSVertexerCosmics::FindVertices()
199 // computes the vertices of the events in the range FirstEvent - LastEvent
200 AliRunLoader *rl = AliRunLoader::GetRunLoader();
201 AliITSLoader* itsLoader = (AliITSLoader*) rl->GetLoader("ITSLoader");
202 itsLoader->ReloadRecPoints();
203 for(Int_t i=fFirstEvent;i<=fLastEvent;i++){
204 // printf("Processing event %d\n",i);
206 FindVertexForCurrentEvent(i);
208 WriteCurrentVertex();
212 //-------------------------------------------------------------------------
213 void AliITSVertexerCosmics::PrintStatus() const
215 // Print current status
216 printf("=======================================================\n");
217 printf(" fMaxDistOnSPD2: %f\n",fMaxDistOnSPD2);
218 printf(" fMaxVtxRadius: %f\n",fMaxVtxRadius);
219 printf(" fMinDist2Vtxs: %f\n",fMinDist2Vtxs);
220 printf(" First layer first and last modules: %d, %d\n",fFirstSPD1,fLastSPD1);
221 printf(" Second layer first and last modules: %d, %d\n",fFirstSPD2,fLastSPD2);
222 printf("=======================================================\n");
224 //-------------------------------------------------------------------------